about two weeks ago my computer started shutting down every hour or so after my son began using the modem to hook his xbox to the internet. The computer would be unhooked from the modem and the xbox hooked up then when I needed the internet we'd unhook the xbox and reconnect the computer and reboot the modem so I could connect. At first it was about an hour before it would shut down but the time got shorter and shorter. Now I can only start the computer in safe mode. When I try a normal start up it shuts down before I can put the password in to log on to windows. The modem is a motorola SB5101 cable modem. The computer operating system is XP Home version 2002 service pack 3. Already cleaned all the dust from inside the case, fans are running, went through the event logs, and corrected the time and date to current. It runs fine in safe mode and safe mode with internet. But when I try a normal start it still shuts down.